It makes Elektra the first quadruple asteroid system discovered to date.

Exactly between the orbits of Mars and Jupiter, we find the so-called asteroid belt. This belt is full of unusual space rocks, which may represent remnants of our early solar system. One of these intriguing asteroids is Elektra. And now researchers have discovered that this chunk of space is home to not one, not two, but even three moons.

The Moons of Elektra

It was already known that there are two moons orbiting around Elektra. But now a team of astronomers has found another satellite orbiting the asteroid.

The Elektra system and its three moons. The two already known moons are shown here by the orange and green bands. The blue orbit concerns the newly discovered moon. Image: ESO/Berdeu et al., Yang et al.

This new third moon of Elektra is tentatively named S/2014 (130) 2 and is just a little closer to Elektra than the other two moons. For example, it swims laps just under 350 kilometers away and completes a circle around the mother’s body every 16.3 hours. The moon also has a rather surprising inclined orbit compared to its sisters and the axis of rotation of Elektra itself.

Quadruple Asteroid System

The discovery of a third moon is very special. Because it is the first time that astronomers have come across an asteroid that contains no fewer than three moons. It makes Elektra the first quadruple asteroid system found to date.

Discovery

The research team tracked down Elektra’s new moon thanks to observations made with the SPHERE instrument on the Very Large Telescope of the European Southern Observatory (ESO) in Chile (see box). This instrument is a powerful device that astronomers normally use to hunt for new planets.

More about SPHERE
As mentioned, the new results are due to the advanced Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE) mounted on ESO’s Very Large Telescope. SPHERE has already successfully imaged several planets in orbits around stars other than the Sun. For example, the instrument made the first direct images of two planets orbiting a twin sister of our sun. It also previously discovered one of the most massive planets around a binary star that has at least six times the mass of the sun.

In addition, research leader Anthony Berdeu developed a new algorithm that would allow him to better process the data from SPHERE. SPHERE’s sensitivity, coupled with advanced data processing techniques, allowed the team to uncover Elektra’s newest satellite.

elude

What makes the discovery especially noteworthy is that the researchers used the same data set with which astronomers previously discovered Elektra’s second moon. The fact that the third moon had eluded the research team at the time can easily be explained. For example, it cannot be detected using regular data processing techniques. Berdeu’s new algorithm is therefore a major step forward. Because the algorithm can further expand the capacity of instruments. And that then allowed the team to pick up even the faint signal from Elektra’s third moon.

Berdeu’s newly developed algorithm therefore has a lot of potential. Because if he hadn’t applied this to the Elektra dataset, we wouldn’t have known about a third moon around the asteroid today. It means there may still be many new celestial bodies waiting to be discovered in the mountains of archival data collected by the SPHERE instrument.